International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395-0056
Volume: 07 Issue: 02 | Feb 2020
p-ISSN: 2395-0072
www.irjet.net
Comparative Analysis of Seismic Performance of R.C Building Resting on Plain and Sloping Ground M. Afzal Ahmad1, P. O. Modani2 1Student,
M.E Structure, Dept. of Civil Engineering, PLITMS, Buldana, Maharashtra, India Dept. of Civil Engineering, PLITMS, Buldana, Maharashtra, India ---------------------------------------------------------------------***--------------------------------------------------------------------2Professor,
Abstract - Hilly areas buildings are required to be
constructed on sloping ground due to scarcity of the plain ground. The buildings are irregularly situated on hilly slopes in earthquake prone areas like northeast region of India. These buildings are poorly damaged when subjected to earthquake ground motions and resulted in loss of life and property. Since these buildings are unsymmetrical in nature, hence attract large amount of shear forces and torsional moments, and show unequal distribution due to varying column lengths. In present study, different patterns of buildings which are located in hilly area have been modeled and analyzed using ETABS software based on finite element analysis. A parametric analytical study has been carried out, in which buildings resting on plain and sloping ground are geometrically varied in length and width. In this project total four analytical models of Plain ground building, Sloping ground buildings with 15 degree, 25 degree, 35 degree slopes. Key Words: Hill buildings, Response spectrum method, Plain building, Fundamental time period
1. INTRODUCTION Now a days, rapid construction is taking place in hilly areas due to scarcity of plain ground. As a result the hilly areas have marked effect on the buildings in terms of style, material and method of construction leading to popularity of multi-storeyed structures in hilly regions. Due to sloping profile, the various levels of such structures towards the hill slope and may also have setback also at the same time. Vibrations which causes disturbance in the earth’s surface induced by waves generated inside the earth are termed as earthquakes. It is well known that earthquake ground motions results primarily from the three factors, namely, source characteristics, propagation of waves and local site conditions. When an earthquake of certain magnitude strikes a structure, they induce motions in the structure which depends upon the structure’s vibration characteristics and the location of structure. If a lightweight flexible building is constructed on a foundation which is very stiff, assumption is that the input motion at the base of the structure is same as free field motion. If a huge and rigid structure rests on a relatively soft foundation, the motion at the base of the structure will be different from free-field motion.[1]
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Structure subjected to seismic/earthquake forces are always vulnerable to damage and if it occurs on a sloped building as on hills which is at some inclination to the ground the chances of damage increases much more due to increased lateral forces on short columns on uphill side and thus leads to the formation of plastic hinges. Structures on slopes differ from those on plains because they are irregular horizontally as well as vertically. In north and northeastern parts of India have large scale of hilly terrain which falls in the category of seismic zone IV and V. In the work, a parametric study has been buildings resting on sloping ground are geometrically varied in length width and height. Total four analytical models are analyzed using Response Spectrum Method. Analysis results in terms of modal time period, diaphragm acceleration, diaphragm displacement, maximum bending moment, storey shear and storey drifts. At end, the suitability of different geometry of buildings resting on sloping ground has been suggested.[8]
2. GEOMETRICAL PROPERTIERS All the models have same geometrical and material properties, and rest on the different inclination of ground which is 15 degree, 25 degree and 35 degree . The geometrical properties of the structural elements in the models with designation of different model types. The interstorey height is taken as 3.1 meters and foundation depth is 1.9 m in all the buildings. The thickness of the slab at all floors in all the models is considered as 125 mm. Since, the models are varied in length along and across the slope, their heights will also be varied accordingly, variation in length of configurations along the slope is carried out from five bays (5 m each). The length of building types, across the slope is altered from two bay (5 m each) to five bays of same length at one bay at a time by keeping the same number of bays along slope and number of storeys in the structure.
2. 1 Modeling of Buildings The building is modeled using the finite element software ETABS Version 16.2.0. The analytical models of the building include all components that influence the mass, strength, stiffness and deformability of structure. The building structural system consists of beams, columns, slab, walls, and foundation. The non-structural elements that do not significantly influence the building behavior are not modeled. Beams and columns are modeled as two noded beam element with six DOF at each node. The floor slabs are assumed to act
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